Vehicle locks are used to keep an automobile vehicle door in the closed position. For purposes of this application, the word “door” should be interpreted to extend to any vehicle closure, such as a door, a trunk, a lift gate, etc. The locks allow the door to be opened by operating an internal or external manipulator, such as a key, linked to the lock and operable by a user. Typically, the locks are mounted in the vehicle door and include a claw mechanism designed to release or engage a cooperating means with respect to the lock to unlock and lock the door, respectively. The claw mechanism is urged into its closing position by the cooperating means when the door is closed. A pawl prevents the claw from returning to its release position and keeps the lock in the closed position if the lock is not subject to any release action by, for example, a release control. A vehicle will have both internal and external release controls, such as actuatable door handles.
The lock includes an internal or external release lever to connect the lock to a corresponding internal or external release control. Locking the lock prevents the lock from being opened through actuation of the external release control, while unlocking the lock allows the lock to be opened when the external release control is actuated. In the case of an automobile vehicle door, these operations are conventionally performed using a fascia pull or electromechanical actuator. For mechanical locking, generally, it is necessary to provide a linkage between the lock and a key cylinder.
Using a key cylinder raises several following problems, however. A key cylinder represents a considerable architectural constraint: the introduction of an object into the window seal can allow a thief to act on the lock-key cylinder linkage to break into the vehicle. This problem may be resolved by bringing the key cylinder and lock closer together, but this solution imposes a constraint on the relative position of the key cylinder and the lock. The problem may also be resolved by providing a linkage between the key cylinder and the lock that resists manipulation through the window seal, but this constrains the linkage movement. The position of the key cylinder is also constrained by the need to ensure that the key cylinder does not block the path of the window glass when it is lowered into the door.
The presence of a key cylinder also creates a mechanical constraint. One way of breaking into a vehicle involves tearing the key cylinder from the vehicle door. This is sometimes solved by strengthening the sheet-metal of the door around the lock area, but this adds weight and bulk to the vehicle door. In all of the cases described above, the keys employed in vehicle locks can be easily copied, further adding potential security problems.
Electronic remote controls are known ways to lock and unlock vehicle doors.
Remote controls are usually battery-powered and operate at high frequencies, such as 315, 433 or 865 MHz. Remote opening systems can operate over ranges on the order of 10 m and are usually supplemented by conventional locks to ensure that locking is always possible even if the remote control or its receiver should fail.
One vehicle, the Peugeot 406, has a key that includes a transponder (a passive circuit) that is remotely powered and can be remotely interrogated. The circuit that powers and interrogates the transponder is disposed in the vehicle and prevents the vehicle from starting if the transponder is not responding. In this application, the power feed and disabling circuit is designed to interrogate the transponder when the key is close to the vehicle steering wheel. The circuit operates at frequencies around 125 kHz, i.e., low frequencies, with a range on the order of 5 cm.
French patent 2,740,501 discloses a hands-free system for unlocking and/or opening an automobile vehicle trunk. One or two antennae are provided on the vehicle. Presenting a transponder to the antenna or antennae in a predetermined sequence causes unlocking and/or opening of the trunk. The system disclosed in this patent requires powering by the vehicle battery to achieve unlocking and opening and consequently requires the vehicle to be provided with a cylinder lock as a backup should the hands-free system fail.
U.S. Pat. No. 5,134,392 discloses a keyless opening system. The opening system employs a transmitter powered by a long-life battery.
There is considerable resistance in the art against eliminating the mechanical key cylinder, which makes opening the vehicle possible even if the radio control should fail.
European Patent Application 0,694,644 discloses an electrically-released automobile vehicle lock. Lock opening is provided electrically by operating an actuator powered by the vehicle battery. A standby power source, such as a standby battery, is built into the door associated with the lock. If the electrical power supply from the vehicle battery fails, the lock can still be opened using electrical power supplied by the standby battery. This document says nothing about employing a key cylinder in its system.
This proposed solution poses a problem with the proper dimensions of the lock opening because the motor should allow the lock to be released under both normal conditions and degraded (e.g., post-impact) conditions. The motor and its speed reduction gear are therefore designed to allow opening under degraded conditions, leading to both electrical and mechanical over-dimensioning with respect to requirements under normal conditions. Motor dimensioning consequently presents a problem for standby powering because motor should be supplied with the energy needed for release under heavy loads, but this amount of energy is excessive and wasteful for normal operating conditions.
U.S. Pat. No. 5,552,641 and European Patent Application 1,052,353 disclose locking systems for automobile vehicles based on portable transponders. These documents do not discuss what type of lock is employed in the vehicle. International Application WO-A-0123695 discloses a transmitter for operating a vehicle locking system. Contacts are provided on the transmitter as a way of overcoming failure of the transmitter or vehicle battery.
Other documents disclose locks with electrical or mechanical releases, including European Patent Application 0,589,158, European Patent Application 0,828,049, German Patent Application 196 00 524 and International Application WO-A-01/66889.
There is consequently a need for an automobile vehicle unlocking system that overcomes the disadvantages of purely mechanical locking systems and avoids the architectural and mechanical constraints caused by mechanical systems.